Introduction: Over the past decade, a new technique called cortical screw fixation has been developed, which allows for medialized screw placement through stronger cortical bone. Numerous studies have proven biomechanical equivalence or superiority for cortical screw versus pedicle screw fixation, but few have examined clinical outcomes.

Methods: We prospectively looked at the senior author’s patients who underwent cortical versus pedicle screw fixation between 2013 and 2015 for lumbar degenerative disease. Eighteen patients underwent cortical screw fixation, and 15 patients underwent traditional pedicle screw fixation. We looked at postoperative pain, Oswestry Disability Index (ODI) and Roland Morris (RM) scoring pre and post-operatively, and fusion rates. An independent neuroradiologist assessed fusion by dynamic X-Rays.

Results: The cortical screw cohort showed a trend towards having less peak postoperative pain (7.9 versus 9, p = 0.09). The average postoperative pain was similar between the two cohorts (4.7 vs 4.6, p = 0.93). There was also no difference in pain six to 12 weeks after surgery (4.9 vs 4.9, p = 0.8). However, at six to eight months, the cortical screw cohort had worse pain compared to the pedicle screw cohort (6.1 vs 3.8, p = 0.02). Cortical screw fixation resulted in a mean decrease of 27 from baseline ODI at 6-8 months (P = 0.014), with a 70% fusion rate at 14.7 months.

Conclusions: The cortical screw patients showed a trend towards less peak pain in the short-term (one to three days post-surgery) and more pain in the long-term (six to eight months post-surgery) compared to pedicle screw patients. Both cohorts had a statistically significant reduction in pain levels compared to preoperative pain. Cortical screw fixation resulted in functional outcomes comparable to those seen with traditional pedicle screw fixation for lumbar degenerative disease, with a decrease of 27 from baseline ODI at 6-8 months.

Patient Care: We hope that a better understanding of cortical screws will lead to improved patient outcomes, less postoperative pain, and shorter admission times.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the trajectory and placement of cortical screws, 2) Describe the clinical outcomes of cortical screws, including postoperative pain, fusion rates, and ODI

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